Plasma processing apparatus and plasma processing method

Abstract

A plasma processing apparatus including a processing chamber; a first radio frequency power supply configured to supply, to a sample stage on which the sample is placed, a first radio frequency power; a second radio frequency power supply configured to supply, to the sample stage, a second radio frequency power having a frequency higher than a frequency of the first radio frequency power; and a control device configured to control the first radio frequency power supply and the second radio frequency power supply such that the supply of one radio frequency power is stopped while the other radio frequency power is supplied, in which the frequency of the first radio frequency power and the frequency of the second radio frequency power are defined based on a half-value width of a peak value of an ion energy distribution with respect to the frequency.

The invention claimed is: 
     
       1. A plasma processing apparatus comprising:
 a processing chamber in which a sample is plasma-processed; 
 a radio frequency power supply configured to supply a radio frequency power for generating plasma; 
 a first radio frequency power supply configured to supply, to a sample stage on which the sample is placed, a first radio frequency power; 
 a second radio frequency power supply configured to supply, to the sample stage, a second radio frequency power having a frequency higher than a frequency of the first radio frequency power; and 
 a control device configured to control the first radio frequency power supply and the second radio frequency power supply such that the supply of one radio frequency power is stopped while the other radio frequency power is supplied, wherein 
 the frequency of the first radio frequency power and the frequency of the second radio frequency power are defined based on a full width at half maximum of a peak value of an ion energy distribution with respect to the frequency. 
 
     
     
       2. The plasma processing apparatus according to  claim 1 , wherein
 the frequency of the second radio frequency power is a frequency at which the full width at half maximum is the same as the full width at half maximum at the frequency of the first radio frequency power. 
 
     
     
       3. The plasma processing apparatus according to  claim 2 , wherein
 the frequency of the first radio frequency power and the frequency of the second radio frequency power are defined based on an impedance of a sheath on the sample. 
 
     
     
       4. The plasma processing apparatus according to  claim 3 , wherein
 the frequency of the first radio frequency power and the frequency of the second radio frequency power are frequencies at which a difference in the sheath impedance at the frequency of the first radio frequency power and the sheath impedance at the frequency of the second radio frequency power is large. 
 
     
     
       5. The plasma processing apparatus according to  claim 4 , wherein
 the frequency of the first radio frequency power and the frequency of the second radio frequency power are values defined based on a time during which an ion passes through the sheath. 
 
     
     
       6. The plasma processing apparatus according to  claim 5 , wherein
 the frequency of the first radio frequency power and the frequency of the second radio frequency power are values equal to or less than an inverse number of the time during which the ion passes through the sheath. 
 
     
     
       7. The plasma processing apparatus according to  claim 6 , wherein
 the frequency of the second radio frequency power is 3 MHz or less. 
 
     
     
       8. A plasma processing method, which uses a plasma processing apparatus including a processing chamber in which a sample is plasma-processed, a radio frequency power supply configured to supply a radio frequency power for generating plasma, a first radio frequency power supply configured to supply, to a sample stage on which the sample is placed, a first radio frequency power, and a second radio frequency power supply configured to supply, to the sample stage, a second radio frequency power having a frequency higher than a frequency of the first radio frequency power, the plasma processing method comprising:
 controlling the first radio frequency power supply and the second radio frequency power supply such that the supply of one radio frequency power is stopped while the other radio frequency power is supplied; 
 setting a pressure in the plasma processing to a pressure at which a mean free path of an ion is longer than a sheath thickness on the sample; 
 defining the frequency of the first radio frequency power and the frequency of the second radio frequency power based on a -full width at half maximum of a peak value of an ion energy distribution with respect to the frequency; and 
 etching the sample based on the control of the first and second radio frequency power supplying or stopping in the step of controlling the first radio frequency power supply and the second radio frequency power supply, the plasma processing pressure set in the step of setting the pressure, and the frequency of the first radio frequency power and the frequency of the second radio frequency power defined in the step of defining the frequency of the first radio frequency power and the frequency of the second radio frequency power. 
 
     
     
       9. The plasma processing method according to  claim 8 , further comprising:
 setting the frequency of the second radio frequency power to a frequency at which the -full width at half maximum is the same as the -full width at half maximum at the frequency of the first radio frequency power. 
 
     
     
       10. The plasma processing method according to  claim 9 , further comprising:
 setting the frequency of the first radio frequency power and the frequency of the second radio frequency power to a value equal to or less than an inverse number of a time during which the ion passes through the sheath on the sample. 
 
     
     
       11. The plasma processing method according to  claim 10 , further comprising:
 setting the pressure in the plasma processing to 2.66 Pa or less.